The extent of the world coffee market

This paper employs a novel method to determine whether the prices of various types of coffee are co-integrated. In the spirit of Stigler's arbitrage definition of the market, an attempt is made to test whether all the prices co-integrate in pairs, implying that there is a single market for coffee. This test for co-integration is carried out using both linear and non-linear approaches. This finding demonstrates that the conclusions drawn from the linear and non-linear tests may be drastically different.